Many recently developed projection display systems use spatial light modulators to directly produce the display image. Spatial light modulators are generally formed as an array of X by Y elements. The elements may be physical elements, such as in liquid crystal displays (LCDs), or may be a region of an imaging surface that is activated by a particular addressing scheme. In active matrix displays, the circuitry that activates the element or the region is referred to here as the pixel circuit.
The physical design of digital pixel circuits is generally rectangular in shape when the area of the pixel circuit is minimized. Generally, in high resolution projection displays, it is desirable that the picture elements (pixels) be square. To make a square pixel with a rectangular shaped pixel circuit, the pixel pitch becomes the long dimension of the pixel circuit. This results in pixel circuit area that is not utilized, and pixels that are larger than would otherwise be possible, both adding to the expense of the spatial light modulator
In some systems, lenses are used to magnify the image on the face of the spatial light modulator. In these types of systems, it may be advantageous to have a spatial light modulator with a pixel pitch that is as small as possible. This may be hampered by the pixel circuitry minimization as discussed above.